• 의료ㆍ복지 건축 : 한국의료복지건축학회 논문집
• /
• 제29권3호
• /
• pp.29-36
• /
• 2023

Purpose: The purpose of this study is to find out whether the color change of the LED light source has a significant effect on the beta wave activity of EEG in the learning state. Methods: The subjects of the experiment were 20 male and female college students between the ages of 19 and 25 who routinely perform their studies. In the created learning environment, the EEG change according to the change in the lighting color was measured while solving the Mensa thinking ability problem while sitting on a desk with LED lights installed on the top and a chair with a footrest to stabilize the legs. The light source consisted of 3 ready-made colors and 6 newly created colors. A total of 9 color light stimuli were given for 2 minutes each, and the EEG change of the subject was observed. After the experiment, the correlation was analyzed based on the mid-beta wave data recorded on the QEEG according to the color change of light and the Mensa problem score. Results: It was found that the activation of mid-beta waves was stimulated in the temporal lobes (T5, T3, T6, T4) and occipital lobes (O1, O2) of all subjects who focused on solving Mensa thinking problems. As a result of comparing the top 20% and the bottom 20% of problem solving scores, the upper group had no effect of lighting, while the lower group showed increased beta wave activity in response to color light stimulation in the order of T4, T6, and T5. Implications: It was confirmed that the color of light that activates the middle beta wave varies greatly depending on the subject's attention and learning ability, and it is judged that the color of light including the green wavelength is helpful in activating the middle beta wave in the group with low learning ability.

• 한국전자파학회:학술대회논문집
• /
• 한국전자파학회 2002년도 종합학술발표회 논문집 Vol.12 No.1
• /
• pp.69-73
• /
• 2002

We have designed and fabricated a low-cost, V-band CPW receiver chip set using GaAs PHEMT technology for the application of millimeter-wave wireless communication systems. Low noise amplifiers and down-converters were developed for this chip set. The fabricated low noise amplifier showed an S$\sub$21/ gain of 14.9 ㏈ at 60 ㎓ and a noise figure of 4.1 ㏈ at 52 ㎓. The down-converter exhibited a high conversion gain of 2 ㏈ at the low LO Power of 0 ㏈m. This work demonstrates that the GaAs PHEMT technology is a viable low-cost solution for V-band applications.

• 한국해양공학회지
• /
• 제24권3호
• /
• pp.21-30
• /
• 2010

This study presents a numerical simulation of sea water-exchange as a preliminary accessing tool of water quality in the protected shore behind a overtopped breakwater. The overtopped breakwater is taken into account for a safe swimming and beach protection. The overtopping rate is calculated by empirical models and the consequent currents, known as wave-induced currents, are calculated under the conditions of H.W.O.S.T and L.W.O.S.T. The rate of sea water exchange is used to evaluate the characteristics of sea water exchange and calculated through the simulation processes such as advective discharging through the outlets and random-walking diffusion of particles released within a basin. The numerical results show that the overtopped waves sufficiently improve the water exchange without healthless stagnation of contaminated mass and the consequent currents are not too strong for swimming.

• 대한토목학회논문집
• /
• 제34권3호
• /
• pp.873-883
• /
• 2014

본 연구는 선박의 크기, 계류상태, 파랑의 주기, 파향 등의 영향을 반영하여 계류선박의 동요량을 계산하고, 그 결과를 이용하여 선석 전면에서 하역한계파고를 산정하는 방법을 제시한 것이다. 여기서는 포항신항의 제 8부두에 본 방법을 적용하고 하역중단시 현지 파랑 관측자료와 비교하여 그 타당성을 검증하였다. 하역중단시 현지 선박의 크기는 800~35,000ton이었으며, 이 때 관측된 파랑은 파고 0.10~0.75m, 주기 7~13s이었다. 본 방법에 의한 하역한계파고는 5,000ton, 10,000ton, 30,000ton 선박에 대하여 파고 0.19~0.50m, 주기 8~12s로 계산되었으며, 본 방법은 파랑의 주기 변화 및 선박의 크기에 대응하여 하역중단시 현지 파랑 관측 결과를 잘 재현하였다. 한편 본 방법에 의한 하역한계파고는 선형 5,000~30,000ton, 주기 12s, 선박에 입사하는 파랑의 각도가 $75^{\circ}C$일 때, 설계기준의 하역한계파고에 비해서 장 단주기 파를 고려하면 16~62%, 단주기 파랑만 고려하면 0~46% 감소하였다. 또한 설계기준에 제시된 하역한계파고는 주기 변화 및 선형에 따라 대응하지 못하며, 10,000ton 이하의 선박에 대해서는 과대 평가되어 있음을 확인하였다.

• Structural Engineering and Mechanics
• /
• 제78권1호
• /
• pp.23-30
• /
• 2021

In this paper, we established the generalized thermoelasticity phenomenon in an isotropic elastic medium considering the electromagnetic field, rotation and two-temperature. Three theories of generalized thermoelasticity have been applied: Lord-Shulman (one relaxation time), Green-Lindsay (two relaxation times), as well as the coupled theory. We discussed some particular cases in the context of the wave propagation phenomenon in thermoelasticity. From solving the fundamental equations, we arrived that there are three waves: P-, T- and SV-waves that we calculated their velocities. The boundary conditions for mechanical stress and Maxwell's stress and thermal insulated or isothermal have been applied to determine the amplitudes ratios (reflection coefficients) for P-, T - and SV waves. Some utilitarian aspects are obtained from the reflection coefficients, presented graphically, and the new conclusions have been presented. Comparisons are made for the results predicted by different theories (CT, LS, GL) in the absence and presence of the electro-magnetic field, rotation, as well as two-temperature on the reflection of generalized thermoelastic waves. The results obtained concluded that the external parameters as the angle of incidence, electromagnetic field, rotation as well as the theories parameters have strong effect on the phenomenon.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2000년도 학술대회 논문집 전문대학교육위원
• /
• pp.85-88
• /
• 2000

This paper was development a discharge lamp ballast in order to wave improvement of high power factor and high efficiency. The discharge lamp ballast consists of a power factor correction circuit and a correction circuit on switching frequency of inverter. Instead of passive power factor circuit, active power factor circuit is adopted. Because it has the advantage of size, weight, total harmonic distortion, out DC voltage regulation, and power factor. The power factor circuit with MG34262 is controlled by variable frequency discontinuous mode. Results experiments, discharge lamp ballast is showed to have excellent for the proposed electronic ballast's operation and characteristics.

• 대한수학회지
• /
• 제61권4호
• /
• pp.797-836
• /
• 2024

We consider the following strongly damped wave equation on ℝ³ with memory u_tt - αΔu_t - βΔu + λu - ∫₀^∞ κ'(s)∆u(t - s)ds + f(x, u) + g(x, u_t) = h, where a quite general memory kernel and the nonlinearity f exhibit a critical growth. Existence, uniqueness and continuous dependence results are provided as well as the existence of regular global and exponential attractors of finite fractal dimension.

• 한국추진공학회:학술대회논문집
• /
• 한국추진공학회 2005년도 제25회 추계학술대회논문집
• /
• pp.422-425
• /
• 2005

가로 등방성 복합재료에서 반사되거나 굴절된 파동의 속도와 입자방향, 그리고 진폭을 운동방정식과 구성방정식 그리고 파동수와 진동수로 표현된 변위식을 사용하여 구하였다. Snell 법칙을 사용하여 Eigenvalue 문제를 풀어 파동속도를 구하였으며 그 결과는 T300 Carbon fiber/5208 Epoxy 재료 성질을 이용하여 검증하였다. 이러한 분석은 수분 침수 C-scan을 이용하여 가로등방성 복합재료의 결점을 찾아내는데 응용될 수 있다.

• 한국해양공학회:학술대회논문집
• /
• 한국해양공학회 2004년도 학술대회지
• /
• pp.85-89
• /
• 2004

The wave interactions with fully submerged and floating dual buoy/vertical porous membrane breakwaters has been investigated in experimentally to validate the developed theory and numerical method in the previous study, in which multi-domain hydro-elastic formulation was carried out in the context of linear wave-body interaction theory and Darcy's law. It is found that the experimental results agrees well with the numerical prediction. Transmission and reflection can be quite reduced simultaneously especially in the region of long waves. The properly tuned system to incoming waves can effectively dissipate wave energy and also offset each other between incident and scattered waves using its hydro-elasticity and geometry.

• 대한의용생체공학회:의공학회지
• /
• 제17권2호
• /
• pp.235-240
• /
• 1996

The automated ECG diagnostic systems that are odd in hospitals have low performance of P-wave detection when faced with some diseases such as conduction block. So, the purpose of this study was the improvement of detection performance in conduction block which is low in P-wave detection. The first procedure was removal of baseline drift by subtracting the median filtered signal of 0.4 second length from the original signal. Then the algorithm detected R peak and T end point and cancelled the QRS-T complex to get'p prototypes'. Next step was magnification of P prototypes with dispersion and detection of'p candidates'in the magnified signal, and then extraction of contextual information concerned with P-waves. For the last procedure, the CIR was applied to P candidates to confirm P-waves. The rule base consisted of three rules that discriminate and confirm P-waves. This algorithm was evaluated using 500 patient's raw data P-wave detection perFormance was in- creased 6.8% compared with the QRS-T complex cancellation method without application of the rule base.